Water-dispersible polymers, a method of making same and items using same

ABSTRACT

The present invention is directed to water-dispersible polymers. The present invention is also directed to a method of making water-dispersible polymers and their applicability as binder compositions. The present invention is further directed to fiber-containing fabrics and webs comprising water-dispersible binder compositions and their applicability in water-dispersible personal care products.

FIELD OF THE INVENTION

[0001] The present invention is directed to water-dispersible polymerformulations. The present invention is also directed to a method ofmaking water-dispersible polymer formulations and their applicability asbinder compositions for disposable items. The present invention isfurther directed to disposable items, such as wet-wipes, comprisingwater-dispersible binder compositions.

BACKGROUND OF THE INVENTION

[0002] For many years, the problem of disposability has plaguedindustries that provide disposable items, such as, diapers, wet wipes,incontinent garments and feminine care products. While much headway hasbeen made in addressing this problem, one of the weak links has been theinability to create an economical coherent fibrous web, which willreadily dissolve or disintegrate in water, but still have sufficientin-use strength. See, for example, U.K. patent disclosure 2,241,373 andU.S. Pat. No. 4,186,233. Without such a product, the ability of the userto dispose of the product by flushing it down the toilet is greatlyreduced, if not eliminated. Furthermore, the ability of the product todisintegrate in a landfill is quite limited because a large portion ofthe product components, which may well be biodegradable orphotodegradable, are encapsulated in or bound together by plastic whichdegrades over a long period of time, if at all. Accordingly, if theplastic disintegrated in the presence of water, the internal componentscould degrade as a result of the rupture of the plastic encapsulation orbinding.

[0003] Disposable products, such as diapers, feminine care products andadult incontinent care products may be made to be disposed by flushingdown toilets. Usually such products comprise a body side liner whichmust rapidly pass fluids, such as urine or menses, so that the fluid maybe absorbed by an absorbent core of the product. Typically, the bodyside liner may be a coherent fibrous web, which desirably possesses anumber of characteristics, such as softness and flexibility. The fibrousweb of the body side liner material may be typically formed by wet ordry (air) laying a generally random plurality of fibers and joining themtogether to form a coherent web with a binder compositions. Past bindercompositions have performed this function well. However, fibrous webscomprising these compositions tended to be non-dispersible and presentproblems in typical household sanitation systems.

[0004] Recent binder compositions have been developed which can be moredispersible and are more environmentally responsible than past bindercompositions. One class of binder compositions includes polymericmaterials having inverse solubility in water. These binder compositionsare insoluble in warm water, but are soluble in cold water, such asfound in a toilet. It is well known that a number of polymers exhibitcloud points or inverse solubility properties in aqueous media. Thesepolymers have been cited in several publications for variousapplications, including (1) as evaporation retarders (JP 6207162); (2)as temperature sensitive compositions, which are useful as temperatureindicators due to a sharp color change associated with a correspondingtemperature change (JP 6192527); (3) as heat sensitive materials thatare opaque at a specific temperature and become transparent when cooledto below the specific temperature (JP 51003248 and JP 81035703); (4) aswound dressings with good absorbing characteristics and easy removal (JP6233809); and (5) as materials in flushable personal care products (U.S.Pat. No. 5,509,913, issued to Richard S. Yeo on Apr. 23, 1996 andassigned to Kimberly-Clark Corporation).

[0005] Other recent binders of interest include a class of binders,which are ion-sensitive. Several U.S. and European patents assigned toLion Corporation of Tokyo, Japan, disclose ion-sensitive polymerscomprising acrylic acid and alkyl or aryl acrylates. See U.S. Pat. Nos.5,312,883, 5,317,063 and 5,384,189, the disclosures of which areincorporated herein by reference, as well as, European Pat. No.608460A1. In U.S. Pat. No. 5,312,883, terpolymers are disclosed assuitable binders for flushable nonwoven webs. The disclosed acrylicacid-based terpolymers, which comprise partially neutralized acrylicacid, butyl acrylate and 2-ethylhexyl acrylate, are suitable binders foruse in flushable nonwoven webs in some parts of the world. However,because of the presence of a small amount of sodium acrylate in thepartially neutralized terpolymer, these binders fail to disperse inwater containing more than about 15 ppm Ca² ⁺ and/or Mg²⁺. When placedin water containing more than about 15 ppm Ca² ⁺ and/or Mg² ⁺ ions,nonwoven webs using the above-described binders maintain a tensilestrength greater than 30 g/in, which negatively affects the“dispersibility” of the web. The proposed mechanism for the failure isthat each calcium ion binds with two carboxylate groups eitherintramolecularly or intermolecularly. Intramolecular association causesthe polymer chain to coil up, which eventually leads to polymerprecipitation. Intermolecular association yields crosslinking. Whetherintramolecular or intermolecular associations are taking place, theterpolymer is not soluble in water containing more than about 15 ppm Ca²⁺ and/or Mg² ⁺. Due to the strong interaction between calcium ions andthe carboxylate groups of the terpolymer, dissociation of the complex ishighly unlikely because this association is irreversible. Therefore, theabove described polymer that has been exposed to a high Ca² ⁺ and/or Mg²⁺ concentration solution will not disperse in water even if the calciumconcentration decreases. This limits the application of the polymer as aflushable binder material because most areas across the U.S. have hardwater, which contains more than 15 ppm Ca² ⁺ and/or Mg² ⁺.

[0006] In a co-pending application assigned to Kimberly Clark; i.e.,U.S. patent application Ser. No. 09/223,999, filed Dec. 31, 1998, thedisclosure of which is incorporated herein by reference, there isdisclosed a modification of the acrylic acid terpolymers of theabove-referenced patents to Lion Corporation. Specifically, U.S. patentapplication Ser. No. 09/223,999 discloses a sulfonate anion modifiedacrylic acid terpolymers which has improved dispersibility in relativelyhard water; e.g., up to 200 ppm Ca² ⁺ and/or Mg² ⁺, compared to theunmodified Lion polymers. However, the Lion Corporation ion-sensitivepolymers of the above-referenced patents and the sulfonate anionmodified acrylic acid terpolymers of the co-pending application, whenused as binders for personal care products, such as wet wipes, typicallyhave reduced sheet wettability, increased sheet stiffness, increasedsheet stickiness, reduced binder sprayability and relatively highproduct cost.

[0007] Another approach to dispersible personal care products isdisclosed in U.S. Pat. No. 5,281,306 to Kao Corporation of Tokyo, Japan(the disclosure of which is incorporated herein by reference). Thispatent discloses a water-disintegratable cleansing sheet; i.e., wetwipe, comprising water-dispersible fibers treated with a water-solublepolymer binder having a carboxyl group. Examples of water-solublebinders having a carboxyl group include, carboxymethyl cellulose,methacrylic acid-lauryl methacrylate, polyacrylic acid, polymethacrylicacid copolymers of ethyl hexyl acetate, butyl acrylate and acrylic acid,and salts thereof. The cleansing sheet is treated with a cleansing agentcontaining 5%-95% of a water-compatible organic solvent and 95%-5%water. A preferred organic solvent is propylene glycol. The cleansingsheet does not disperse in the organic solvent-based cleansing agent,but disperses in water. The cleansing sheet also includes a metallic ionselected from alkaline earth metals, such as magnesium, calcium,strontium, barium, manganese, zinc, cobalt and nickel. Although the Kaopatent indicates that all polymers containing carboxyl groups maintainwet strength, not all polymers so disclosed, such as polyacrylic acidand salts thereof, satisfactorily maintain wet strength.

[0008] Although many patents disclose various ion and temperaturesensitive compositions for water-dispersible or flushable materials,there exists a need for dispersible products possessing softness,flexibility, three dimensionality, and resiliency; wicking andstructural integrity in the presence of body fluids (including feces) atbody temperature; and true fiber dispersion after toilet flushing sothat fibers do not become entangled with tree roots or at bends in sewerpipes. In addition, the known ion-sensitive polymers, such as those ofLion Corporation and the co-pending application of Kimberly Clark, haverelatively high viscosities at high shear rates that make application byspraying impossible or impractical. Moreover, there is a need in the artfor flushable products having water-dispersibility in all areas of theworld, including soft and hard water areas. Furthermore, there is a needfor water-dispersible binders that do not reduce wettability of productwith which they are used and are sprayable for easy and uniformapplication to and penetration into products.

SUMMARY OF THE INVENTION

[0009] The present invention is directed to polymer formulations, whichhave been developed to address the above-described problems associatedwith currently available, water-dispersible polymers and other polymersdescribed in literature. The polymer formulations of the presentinvention are insoluble in a wetting composition comprising 5%-95% of awater-compatible organic solvent and 95%-5% water, but is soluble inwater, including water containing divalent salt solutions, such as hardwater with up to 200 ppm (parts per million) calcium and magnesium ions.Unlike some water-dispersible polymer binder formulations which lose wetstrength, the polymer formulations of the present invention retainsignificant wet strength. Consequently, flushable products containingthe polymer formulations of the present invention maintain strength whenwetted with a wetting solution, but are dispersibility in hard water.Furthermore, the polymer formulations of the present invention haveimproved properties of sprayability.

[0010] The polymer formulations of the present invention are useful asbinders and structural components for air-laid and wet-laid nonwovenfabrics for applications such as body-side liners, fluid distributionmaterials, fluid in-take materials (surge) or cover stock in variouspersonal care products. The polymer formulations of the presentinvention are particularly useful as a binder material for flushablepersonal care products, particularly wet wipes for personal use such ascleaning or treating skin, makeup removal, nail polish removal, medicalcare, and also wipes for use in hard surface deaning, automotive care,including wipes comprising cleaning agents, disinfectants, and the like.The flushable products maintain integrity or wet strength during storageand use, and break apart or disperse after disposal in the toilet whenthe organic solvent concentration falls below a critical level. Suitablesubstrates for treatment include tissue, such as creped or uncrepedtissue, coform products, hydroentangled webs, airlaid mats, fluff pulp,nonwoven webs, and composites thereof. Methods for producing uncrepedtissues and molded three-dimensional tissue webs of use in the presentinvention can be found in commonly owned U.S. patent application, Ser.No. 08/912,906, “Wet Resilient Webs and Disposable Articles MadeTherewith,” by F. -J. Chen et al., filed Aug. 15, 1997; U.S. Pat. No.5,429,686, issued to Chiu et al. on Jul. 4, 1995; U.S. Pat. No.5,399,412, issued to S. J. Sudall and S. A. Engel on Mar. 21, 1995; U.S.Pat. No. 5,672,248, issued to Wendtet al. on Sept. 30, 1997; and U.S.Pat. No. 5,607,551, issued to Farrington et al. on Mar. 4, 1997; all ofwhich are herein incorporated in their entirety by reference. The moldedtissue structures of the above patents can be especially helpful inproviding good cleaning in a wet wipe. Good cleaning can also bepromoted by providing a degree of texture in other substrates as well byembossing, molding, wetting and through-air drying on a textured fabric,and the like.

[0011] Airlaid material can be formed by metering an airflow containingthe fibers and other optional materials, in substantially dry condition,onto a typically horizontally moving wire forming screen. Suitablesystems and apparatus for air-laying mixtures of fibers andthermoplastic material are disclosed in, for example, U.S. Pat. No.4,157,724 (Persson), issued Jun. 12, 1979, and reissued Dec. 25, 1984 asRe. U.S. Pat. No. 31,775; U.S. Pat. No. 4,278,113 (Persson), issued Jul.14, 1981; U.S. Pat. No. 4,264,289 (Day), issued Apr. 28, 1981; U.S. Pat.No. 4,352,649 (Jacobsen et al.), issued Oct. 5, 1982; U.S. Pat. No.4,353,687 (Hosler, et al.), issued Oct. 12, 1982; U.S. Pat. No.4,494,278 (Kroyer, et al.), issued Jan. 22, 1985; U.S. Pat. No.4,627,806 (Johnson), issued Dec. 9, 1986; U.S. Pat. No. 4,650,409(Nistri, et al.), issued Mar. 17, 1987; and U.S. Pat. No. 4,724,980(Farley), issued Feb. 16, 1988; and U.S. Pat. No. 4,640,810 (Laursen etal.), issued Feb. 3, 1987.

[0012] The present invention also discloses how to makewater-dispersible nonwovens, including cover stock (liner), intake(surge) materials and wet wipes, which are stable in fluids having5%-95% of a water-compatible organic solvent and 95%-5% water, using theabove-described unique polymer formulations as binder compositions. Theresultant nonwovens are flushable and water-dispersible due to the waterdispersibility of the binder. The polymer formulations with which sucharticles are treated can have improved properties of sprayability, whichimproves polymer distribution on the product and penetration into theproduct, in addition to ease of application, which translates into costsavings.

[0013] These and other objects, features and advantages of the presentinvention will become apparent after a review of the following detaileddescription of the disclosed embodiments and the appended drawing andclaims.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS

[0014] In order to be an effective polymer formulation suitable for usein flushable or water-dispersible personal care products, theformulations should desirably be (1) functional; i.e., maintain wetstrength under controlled conditions and dissolve or disperse rapidly insoft or hard water such as found in toilets and sinks around the world;(2) safe (not toxic); and (3) relatively economical. In addition to theforegoing factors, the polymer formulations when used as a bindercomposition for a non-woven substrate, such as a wet wipe, desirablyshould be (4) processable on a commercial basis; i.e., may be appliedrelatively quickly on a large scale basis, such as by spraying, whichthereby requires that the binder composition have a relatively lowviscosity at high shear; and (5) provide acceptable levels of sheet orsubstrate wettability. The wetting composition with which the wet wipesof the present invention are treated can provide some of the foregoingadvantages, and, in addition, can provide (6) improved skin care, suchas reduced skin irritation or other benefits. The polymer formulationsof the present invention and articles made therewith, especially wetwipes comprising particular wetting compositions set forth below, canmeet many or all of the above criteria. Of course, it is not necessaryfor all of the advantages of the preferred embodiments of the presentinvention to be met to fall within the scope of the present invention.

[0015] The polymer formulations of the present invention are formed froma blend of two polymers. One of the polymers of the polymer formulationsof the present invention is a synthetic water-soluble polymer.Water-soluble polymers useful in the present invention includewater-soluble polymer containing carboxylate groups which also haveflexible polymer chains. Such water-soluble polymers are disclosed inU.S. Pat. No. 5,281,306, the disclosure of which is incorporated hereinby reference in its entirety. A useful water-soluble polymer is sodiumpolyacrylate. A sodium polyacrylate useful in the present invention iscommercially available under the designation NS 9893-92A and NS 9893-92Bfrom National Starch and Chemical Co., Bridgewater, N.J.

[0016] Water-soluble acrylic acid copolymers useful in the presentinvention may comprise any combination of acrylic acid monomers andacrylic ester (alkyl acrylate) monomers capable of free radicalpolymerization into a copolymer. Suitable acrylic acid monomers include,but are not limited to, acrylic acid and methacrylic acid. Suitableacrylic monomers include, but are not limited to, acrylic esters andmethacrylic esters having an alkyl group of 1 to 18 carbon atoms or acycloalkyl group of 3 to 18 carbonatoms and it is preferred that acrylicesters and/or methacrylic esters having an alkyl group of 1 to 12 carbonatoms or a cycloalkyl group of 3 to 12 carbon atoms may be used singlyor in combination.

[0017] The relative amounts of the monomers in the acrylic acidcopolymer of the present invention may vary depending on the desiredproperties in the resulting polymer. The mole percent of acrylic acidmonomer in the copolymer is up to about 70 mole percent. Morespecifically, the mole percent of acrylic acid monomer in the copolymeris from about 15 to about 50 mole percent. Most specifically, the molepercent of acrylic acid monomer in the copolymer is from about 25 toabout 40 mole percent.

[0018] More specifically, examples of the acrylic acid copolymers usefulin the present invention include copolymers of 10 weight percent to 90weight percent, desirably 20 weight percent to 70 weight percent ofacrylic acid and/or methacrylic acid and 90 weight percent to 10 weightpercent, desirably 80 weight percent to 30 weight percent of acrylicesters and/or methacrylic esters having an alkyl group of 1 to 18 carbonatoms or a cycloalkyl group of 3 to 18 carbon atoms in which 1 to 60mole percent, desirably 5 to 50 mole percent of acrylic acid and/ormethacrylic acid is neutralized to form a salt; or copolymers of 30weight percent to 75 weight percent, desirably 40 weight percent to 65weight percent of acrylic acid, 5 weight percent to 30 weight percent,desirably 10 weight percent to 25 weight percent of acrylic estersand/or methacrylic esters having an alkyl group of 8 to 12 carbon atomsand 20 weight percent to 40 weight percent; desirably 25 weight percentto 35 weight percent of acrylic esters and/or methacrylic esters havingan alkyl group of 2 to 4 carbon atoms in which 1 to 50 mole percent,desirably 2 to 40 mole percent of acrylic acid is neutralized to form asalt.

[0019] The acrylic acid copolymers of the present invention may have anaverage molecular weight, which varies depending on the ultimate use ofthe polymer. The acrylic acid copolymers of the present invention have aweight average molecular weight ranging from about 10,000 to about5,000,000. More specifically, the acrylic acid copolymers of the presentinvention have a weight average molecular weight ranging from about25,000 to about 2,000,000, or, more specifically still, from about200,000 to about 1,000,000.

[0020] The acrylic acid copolymers of the present invention may beprepared according to a variety of polymerization methods, desirably asolution polymerization method. Suitable solvents for the polymerizationmethod include, but are not limited to, lower alcohols such as methanol,ethanol and propanol; a mixed solvent of water and one or more loweralcohols mentioned above; and a mixed solvent of water and one or morelower ketones such as acetone or methyl ethyl ketone.

[0021] In the polymerization methods of the present invention, anypolymerization initiator may be used. Selection of a particularinitiator may depend on a number of factors including, but not limitedto, the polymerization temperature, the solvent, and the monomers used.Suitable polymerization initiators for use in the present inventioninclude, but are not limited to, 2,2′-azobisisobutyronitrile,2,2′-azobis(2-methylbutyronitrile),2,2′-azobis(2,4-dimethylvaleronitrile),2,2′-azobis(2-amidinopropane)dihydrochloride,2,2′-azobis(N,N′-dimethyleneisobutylamidine), potassium persulfate,ammonium persulfate, and aqueous hydrogen peroxide. The amount ofpolymerization initiator may desirably range from about 0.01 to 5 weightpercent based on the total weight of monomer present.

[0022] The polymerization temperature may vary depending on thepolymerization solvent, monomers, and initiator used, but in general,ranges from about 20° C. to about 90° C. Polymerization time generallyranges from about 2 to about 8 hours.

[0023] If polyacrylic acid is used as one of the monomers, it is desiredto neutralize at least a portion of the acid component. Any inorganicbase or organic base may be used as a neutralizing agent to neutralizethe acid component. Examples of neutralizing agents include, but are notlimited to, inorganic bases, such as sodium hydroxide, potassiumhydroxide, lithium hydroxide and sodium carbonate, and amines, such asmonoethanolamine, diethanolamine, diethylaminoethanol, ammonia,trimethylamine, triethylamine, tripropylamine, morpholine. Preferredneutralizing agents include sodium hydroxide, potassium hydroxide, or acombination thereof.

[0024] In a further embodiment of the present invention, theabove-described water-soluble polymer formulations are used as bindermaterials for flushable and/or non-flushable products. In order to beeffective as a binder material in flushable products throughout theUnited States, the ion-sensitive polymer formulations of the presentinvention remain stable and maintain their integrity while dry or in awetting composition comprising 5%-95% of a water-compatible organicsolvent and 95%-5% water, but is soluble in water, including watercontaining divalent salt solutions, such as hard water with up to 200ppm (parts per million) calcium and magnesium ions. Desirably, theion-sensitive polymer formulations of the present invention includingacrylic acid copolymers are insoluble in a composition comprising 20%water-compatible organic solvent and 80% water.

[0025] As stated above, the polymer formulations of the presentinvention are formed from a combination of two or more differentpolymers, wherein at least one polymer is water-soluble polymer. Thesecond polymer is an emulsion polymer. Furthermore, the emulsion polymermay be insoluble in water and can reduce the shear viscosity of thewater-soluble polymer. Examples of emulsion polymers useful in thepresent invention include, but are not limited to, styrene acrylicemulsions and styrenebutadiene emulsions. Styrene emulsions useful inthe present invention are commercially available under the designationRhoplex P-308 and Rhoplex NW-1715K from Rohm and Haas, Philadelphia, Pa.Styrene-butadiene emulsions useful in the present invention arecommercially available under the designation Rovene 4470, Rovene 4457and Rovene 4817 from Mallard Creek Polymers, Charlotte, N.C.

[0026] In the polymer blend of the present invention, the water-solublepolymer is present in an amount of approximately 50% to 95% by weightand the emulsion polymer is present in an amount of approximately 5% to50% by weight. Desirable, the water-soluble polymer is present in anamount of approximately 70% to 90% by weight and the emulsion polymer ispresent in an amount of approximately 10% to 30% by weight.

[0027] In blending the water-soluble polymer and the emulsion polymer,the sequence of blending is important. One must avoid procedures thatcould shock the surfactant systems of the emulsion polymers. Theprocedure followed in the present invention is to initially dilute thewater-soluble polymer with water. Then, while stirring the dilutedwater-soluble polymer, the emulsion polymer is slowly added to thewater-soluble polymer.

[0028] Desirably, but not necessarily, the emulsion polymer whencombined with the water-soluble polymer will reduce the shear viscosityof the water-soluble polymer to such an extent that the combination ofthe water-soluble polymer and the emulsion polymer is sprayable. Bysprayable is meant that the polymer can be applied to a nonwoven fibroussubstrate by spraying and the distribution of the polymer across thesubstrate and the penetration of the polymer into the substrate are suchthat the polymer formulation is uniformly applied to the substrate.

[0029] The co-binder polymer can be in the form of an emulsion latex.The surfactant system used in such a latex emulsion should be such thatit does not substantially interfere with the dispersibility of thewater-soluble polymer.

[0030] The emulsion polymer of the present invention can have an averagemolecular weight, which varies depending on the ultimate use of thepolymer. Desirably, the emulsion polymer has a weight average molecularweight ranging from about 500,000 to about 200,000,000. More desirably,the emulsion polymer has a weight average molecular weight ranging fromabout 500,000 to about 100,000,000.

[0031] Emulsion polymers that can meet many or all of the foregoingcriteria include, but are not limited to, poly(ethylene-vinyl acetate),poly(styrene-butadiene), poly(styrene-acrylic), a vinyl acrylicterpolymer, neoprene, a polyester latex, an acrylic emulsion latex, polyvinyl chloride, ethylene-vinyl chloride copolymer, a carboxylated vinylacetate latex, and the like. A particularly preferredpoly(styrene-butadiene) is Rovene® 4817 available from Mallard CreekPolymers, Charlotte, N.C. A particularly preferred poly(styrene-acrylic)is Rhoplex® NM 1715K available from Rohm and Haas, Philadelphia, Pa.

[0032] As stated above, useful emulsion polymers can include a varietyof commercial latex emulsions, including those selected from the Rovene®series (styrene butadiene latices available from Mallard Creek Polymersof Charlotte, N.C.), the Rhoplex® latices of Rohm and Haas Company, andthe Elite® latices of National Starch. Polymer emulsions or dispersionsgenerally comprise small polymer particles, such as crosslinkableethylene vinyl acetate copolymers, typically in spherical form,dispersed in water and stabilized with surface active ingredients, suchas low molecular weight emulsifiers or high molecular weight protectivecolloids. These liquid binders can be applied to airlaid webs or othersubstrates by methods known in the art of binder treatment for nonwovenwebs, including spray or foam application, flooded nip impregnation,curtain coating, etc., followed by drying. In general, a wide variety oflatex compounds and other resins or emulsions can be considered,including vinyl acetate copolymer latices, such as 76 RES 7800 fromUnion Oil Chemicals Divisions and Resyn® 25-1103, Resyn® 25-1109, Resyn®25-1119, and Resyn® 25-1189 from National Starch and ChemicalCorporation, ethylene-vinyl acetate copolymer emulsions, such asAirflex® ethylene-vinylacetate from Air Products and Chemicals Inc.,acrylic-vinyl acetate copolymer emulsions, such as Rhoplex® AR-74 fromRohm and Haas Company, Synthemul® 97-726 from Reichhold Chemicals Inc.,Resyn® 25-1140, 25-1141, 25-1142, and Resyn-6820 from National Starchand Chemical Corporation, vinyl acrylic terpolymer latices, such as 76RES 3103 from Union Oil Chemical Division, and Resyn® 251110 fromNational Starch and Chemical Corporation, acrylic emulsion latices, suchas Rhoplex® B-15J, Rhoplex® P-376, Rhoplex® TR-407, Rhoplex® E-940,Rhoplex® TR934, Rhoplex® TR-520, Rhoplex® HA-24, and Rhoplex® NW1825from Rohm and Haas Company, and Hycar® 2600×322, Hycar® 2671, Hycar®2679, Hycar® 26120, and Hycar® 2600×347 from B. F. Goodrich ChemicalGroup, styrene-butadiene latices, such as 76 RES 4100 and 76 RES 8100available from Union Oil Chemicals Division, Tylac® resin emulsion68-412, Tylac® resin emulsion 68-067, 68-319, 68-413, 68-500, 68-501,available from Reichhold Chemical Inc., and DL6672A, DL6663A, DL6638A,DL6626A, DL6620A, DL615A, DL617A, DL620A, DL640A, DL650A available fromDow Chemical Company; and rubber latices, such as neoprene availablefrom Serva Biochemicals; polyester latices, such as Eastman AQ 29Davailable from Eastman Chemical Company; vinyl chloride latices, such asGeon® 352 from B. F. Goodrich Chemical Group; ethylene-vinyl chloridecopolymer emulsions, such as Airflex® ethylene-vinyl chloride from AirProducts and Chemicals; polyvinyl acetate homopolymer emulsions, such asVinac® from Air Products and Chemicals; carboxylated vinyl acetateemulsion resins, such as Synthemul® synthetic resin emulsions 40-502,40-503, and 97-664 from Reichhold Chemicals Inc. and Polyco® 2149, 2150,and 2171 from Rohm and Haas Company. Silicone emulsions can also beconsidered.

[0033] Polymer Formulations and Fabrics Containing the Same

[0034] The polymer formulations of the present invention may be used asbinders. The binder formulations of the present invention may be appliedto any fibrous substrate. The binders are particularly suitable for usein water-dispersible products. Suitable fibrous substrates include, butare not limited to, nonwoven and woven fabrics. In many embodiments,particularly personal care products, preferred substrates are nonwovenfabrics. As used herein, the term “nonwoven fabric” refers to a fabricthat has a structure of individual fibers or filaments randomly arrangedin a mat-like fashion (including papers). Nonwoven fabrics can be madefrom a variety of processes including, but not limited to, air-laidprocesses, wet-laid processes, hydroentangling processes, staple fibercarding and bonding, and solution spinning.

[0035] The binder composition may be applied to the fibrous substrate byany known process of application. Suitable processes for applying thebinder material include, but are not limited to, printing, spraying,electrostatic spraying, coating, flooded nips, metered press rolls,impregnating or by any other technique. The amount of binder compositionmay be metered and distributed uniformly within the fibrous substrate ormay be non-uniformly distributed within the fibrous substrate. Thebinder composition may be distributed throughout the entire fibroussubstrate or it may be distributed within a multiplicity of smallclosely spaced areas. In most embodiments, uniform distribution ofbinder composition is desired.

[0036] For ease of application to the fibrous substrate, the binder maybe dissolved in water, or in a non-aqueous solvent, such as methanol,ethanol, acetone, or the like, with water being the preferred solvent.The amount of binder dissolved in the solvent may vary depending on thepolymer used and the fabric application. Desirably, the binder solutioncontains up to about 25 percent by weight of binder composition solids.More desirably, the binder solution contains from about 10 to 20 percentby weight of binder composition solids, especially about 12 percent byweight binder composition solids. Plasticizers, perfumes, coloringagents, antifoams, bactericides, preservative, surface active agents,thickening agents, fillers, opacifiers, tackifiers, detackifiers, andsimilar additives can be incorporated into the solution of bindercomponents, if so desired.

[0037] Once the binder composition is applied to the substrate, thesubstrate is dried by any conventional means. Once dry, the coherentfibrous substrate exhibits improved tensile strength when compared tothe tensile strength of the untreated wet-laid or dry-laid substrates,and yet has the ability to rapidly “fall apart”, or disintegrate whenplaced in soft or hard water having a relatively high multivalent ionicconcentration and agitated. For example, the dry tensile strength of thefibrous substrate may be increased by at least 25 percent as compared tothe dry tensile strength of the untreated substrate not containing thebinder. More particularly, the dry tensile strength of the fibroussubstrate may be increase by at least 100 percent as compared to the drytensile strength of the untreated substrate not containing the binder.Even more particularly, the dry tensile strength of the fibroussubstrate may be increased by at least 500 percent as compared to thedry tensile strength of the untreated substrate not containing thebinder.

[0038] A desirable feature of the present invention is that theimprovement in tensile strength is effected where the amount of bindercomposition present, “add-on”, in the resultant fibrous substraterepresents only a small portion by weight of the entire substrate. Theamount of “add-on” can vary for a particular application; however, theoptimum amount of “add-on” results in a fibrous substrate which hasintegrity while in use and also quickly disperses when agitated inwater. For example, the binder components typically are from about 5 toabout 65 percent, by weight, of the total weight of the substrate. Moreparticularly, the binder components may be from about 10 to about 35percent, by weight, of the total weight of the substrate. Even moreparticularly, the binder components may be from about 17 to about 22percent by weight of the total weight of the substrate.

[0039] The nonwoven fabrics of the present invention have good in-usetensile strength. Desirably, the nonwoven fabrics of the presentinvention are abrasion resistant and retain significant tensile strengthin aqueous solutions containing greater than about 0.5 weight percentwater-compatible organic solvent. Yet, the nonwoven fabrics aredispersible in very soft to moderately hard to hard water. Because ofthis latter property, nonwoven fabrics of the present invention are wellsuited for disposable products, such as pre-moistened wipes (wet wipes),which can be thrown in a flush toilet after use in any part of theworld.

[0040] The fibers forming the fabrics above can be made from a varietyof materials including natural fibers, synthetic fibers, andcombinations thereof. The choice of fibers depends upon, for example,the intended end use of the finished fabric and fiber cost. Forinstance, suitable fibrous substrates may include, but are not limitedto, natural fibers such as cotton, linen, jute, hemp, wool, wood pulp,etc. Similarly, regenerated cellulosic fibers, such as viscose rayon andcuprammonium rayon, modified cellulosic fibers, such as celluloseacetate, or synthetic fibers, such as those derived from polypropylenes,polyethylenes, polyolefins, polyesters, polyamides, polyacrylics, etc.,alone or in combination with one another, may likewise be used. Blendsof one or more of the above fibers may also beused, if so desired. Amongwood pulp fibers, any known papermaking fibers may be used, includingsoftwood and hardwood fibers. Fibers, for example, may be chemicallypulped or mechanically pulped, bleached or unbleached, virgin orrecycled, high yield or low yield, and the like. Mercerized, chemicallystiffened or crosslinked fibers may also be used.

[0041] Synthetic cellulose fiber types include rayon in all itsvarieties and other fibers derived from viscose or chemically modifiedcellulose, including regenerated cellulose and solvent-spun cellulose,such as Lyocell. Chemically treated natural cellulosic fibers can beused, such as mercerized pulps, chemically stiffened or crosslinkedfibers, or sulfonated fibers. Recycled fibers, as well as virgin fibers,can be used. Cellulose produced by microbes and other cellulosicderivatives can be used. As used herein, the term “cellulosic” is meantto include any material having cellulose as a major constituent, and,specifically, comprising at least 50 percent by weight cellulose or acellulose derivative. Thus, the term includes cotton, typical woodpulps, non-woody cellulosic fibers, cellulose acetate, cellulosetriacetate, rayon, thermomechanical wood pulp, chemical wood pulp,debonded chemical wood pulp, milkweed, or bacterial cellulose. The fiberlength is important in producing the fabrics of the present invention.In some embodiments, such as flushable products, fiber length is of moreimportance. The minimum length of the fibers depends on the methodselected for forming the fibrous substrate. For example, where thefibrous substrate is formed by carding, the length of the fiber shouldusually be at least about 42 mm in order to insure uniformity. Where thefibrous substrate is formed by air-laid or wet-laid processes, the fiberlength may desirably be about 0.2 to 6 mm. Although fibers having alength of greater than 50 mm are within the scope of the presentinvention, it has been determined that when a substantial quantity offibers having a length greater than about 15 mm is placed in a flushablefabric, though the fibers will disperse and separate in water, theirlength tends to form “ropes” of fibers, which are undesirable whenflushing in home toilets. Therefore, for these products, it is desiredthat the fiber length be about 15 mm or less so that the fibers will nothave a tendency to “rope” when they are flushed through a toilet.Although fibers of various lengths are applicable in the presentinvention, desirably fibers are of a length less than about 15 mm sothat the fibers disperse easily from one another when in contact withwater. The fibers, particularly synthetic fibers, can also be crimpedThe fabrics of the present invention may be formed from a single layeror multiple layers. In the case of multiple layers, the layers aregenerally positioned in a juxtaposed or surface-to-surface relationshipand all or a portion of the layers may be bound to adjacent layers.Nonwoven webs of the present invention may also be formed from aplurality of separate nonwoven webs wherein the separate nonwoven websmay be formed from single or multiple layers. In those instances wherethe nonwoven web includes multiple layers, the entire thickness of thenonwoven web may be subjected to a binder application or each individuallayer may be separately subjected to a binder application and thencombined with other layers in a juxtaposed relationship to form thefinished nonwoven web.

[0042] In one embodiment, the fabric substrates of the present inventionmay be incorporated into cleansing and body fluid absorbent products,such as sanitary napkins, diapers, adult incontinence products, surgicaldressings, tissues, wet wipes, and the like. These products may includean absorbent core, comprising one or more layers of an absorbent fibrousmaterial. The core may also comprise one or more layers of afluid-pervious element, such as fibrous tissue, gauze, plastic netting,etc. These are generally useful as wrapping materials to hold thecomponents of the core together. Additionally, the core may comprise afluid-impervious element or barrier means to preclude the passage offluid through the core and on the outer surfaces of the product.Desirably, the barrier means also is water-dispersible. A film of apolymer having substantially the same composition as the aforesaidwater-dispersible binder is particularly well-suited for this purpose.In accordance with the present invention, the polymer compositions areuseful for forming each of the above-mentioned product componentsincluding the layers of absorbent core, the fluid-pervious element, thewrapping materials, and the fluid-impervious element or barrier means.

[0043] The binder formulations of the present invention are particularlyuseful for binding fibers of air-laid nonwoven fabrics. These air-laidmaterials are useful for body-side liners, fluid distribution materials,fluid in-take materials, such as a surge material, absorbent wrap sheetand cover stock for various water-dispersible personal care products.Air-laid materials are particularly useful for use as a pre-moistenedwipe (wet wipe). The basis weights for air-laid non-woven fabrics mayrange from about 20 to about 200 grams per square meter (“gsm”) withstaple fibers having a denier of about 0.5-10 and a length of about 6-15millimeters. Surge, or in-take, materials need better resiliency andhigher loft so staple fibers having about 6 denier or greater are usedto make these products. A desirable final density for the surge, orin-take, materials is between about 0.025 grams per cubic centimeter(“g/cc”) to about 0.10 g/cc. Fluid distribution materials may have ahigher density, in the desired range of about 0.10 to about 0.20 g/ccusing fibers of lower denier, most desirable fibers have a denier ofless than about 1.5. Wipes generally can have a fiber density of about0.025 g/cc to about 0.2 g/cc and a basis weight of about 20 gsm to about150 gsm; specifically from about 30 to about 90 gsm, and mostspecifically from about 60 gsm to about 65 gsm.

[0044] Unlike other binder systems known in the art, the polymerformulations of the present invention can be activated as binderswithout the need for elevated temperature. While drying or water removalis useful in achieving a good distribution of the binder in a fibrousweb, elevated temperature, per se, is not essential because the binderdoes not require crosslinking or other chemical reactions with highactivation energy to serve as a binder. Rather, the interaction with asoluble activating compound, typically a water-compatible organicsolvent, is sufficient to cause the binder to become active (insoluble).Thus, a drying step can be avoided, if desired, or replaced withlow-temperature water removal operations, such as room-temperaturedrying or freeze drying. Elevated temperature is generally helpful fordrying, but the drying can be done at temperatures below what isnormally needed to drive crosslinking reactions. Thus, the peaktemperature to which the substrate is exposed or to which the substrateis brought can be below any of the following: 180° C., 160° C., 140° C.,120° C., 110° C., 105° C., 100° C., 90° C., 75° C., and 60° C., with anexemplary range for peak web temperature of from about 50° C. to about110° C., or from about 70° C. to about 140° C. Of course, highertemperatures can be used, but are not necessary in most embodiments.While polymer systems, such as commercial latex emulsions, may alsocomprise crosslinkers suited for reaction at temperatures of 160° C. orhigher, maintaining a lower peak temperature can be beneficial inpreventing development of excessive strength in the polymer that mightotherwise hinder the water dispersibility of the pre-moistened wipe.

[0045] Wet Wipe Wetting Composition and Wet Wipes Containing the Same

[0046] One particularly interesting embodiment of the present inventionis the production of pre-moistened wipes, or wet wipes, from theabove-described binder compositions and fibrous materials. For wipes,the fibrous material may be in the form of a woven or nonwoven fabric;however, nonwoven fabrics are more desirable. The nonwoven fabric is,desirably, formed from relatively short fibers, such as wood pulpfibers. The minimum length of the fibers depends on the method selectedfor forming the nonwoven fabric. Where the nonwoven fabric is formed bya wet or dry method, the fiber length is desirably from about 0.1millimeters to 15 millimeters. Desirably, the nonwoven fabric of thepresent invention has a relatively low wet cohesive strength when it isnot bonded together by an adhesive or binder material. When suchnonwoven fabrics are bonded together by a binder composition, whichloses its bonding strength in tap water and in sewer water, the fabricwill break up readily by the agitation provided by flushing and movingthrough the sewer pipes.

[0047] The finished wipes may be individually packaged, desirably in afolded condition, in a moisture proof envelope or packaged in containersholding any desired number of sheets in a water-tight package with awetting composition applied to the wipe. The finished wipes may also bepackaged as a roll of separable sheets in a moisture-proof containerholding any desired number of sheets on the roll with a wettingcomposition applied to the wipes. The roll can be coreless and eitherhollow or solid. Coreless rolls, including rolls with a hollow center orwithout a solid center, can be produced with known coreless rollwinders, including those of SRP Industry, Inc. (San Jose, Calif.);Shimizu Manufacturing (Japan), and the devices disclosed in U.S. Pat.No. 4,667,890, issued May 26, 1987 to Gietman. Solid-wound corelessrolls can offer more product for a given volume and can be adapted for awide variety of dispensers.

[0048] Relative to the weight of the dry fabric, the wipe may desirablycontain from about 10 percent to about 400 percent of the wettingcomposition, more desirably from about 100 percent to about 300 percentof the wetting composition, and even more desirably from about 180percent to about 240 percent of the wetting composition. The wipemaintains its desired characteristics over the time periods involved inwarehousing, transportation, retail display and storage by the consumer.Accordingly, shelf life may range from two months to two years.

[0049] Various forms of impermeable envelopes and storage means forcontaining wet-packaged materials, such as wipes and towelettes and thelike, are well known in the art. Any of these may be employed inpackaging the pre-moistened wipes of the present invention.

[0050] Desirably, the pre-moistened wipes of the present invention arewetted with an aqueous wetting composition, which has one or more of thefollowing properties:

[0051] (1) is compatible with the above-described binder compositions ofthe present invention;

[0052] (2) enables the pre-moistened wipe to maintain its wet strengthduring converting, storage and usage (including dispensing), as well as,dispersibility in a toilet bowl;

[0053] (3) does not cause skin irritation;

[0054] (4) reduces tackiness of the wipe, and provides unique tactileproperties, such as skin glide and a “lotion-like feel”; and

[0055] (5) acts as a vehicle to deliver “moist cleansing” and other skinhealth benefits.

[0056] The wetting composition should not act as a solvent for thebinder. However, the wetting composition should contain an amount of awater-compatible organic solvent that preserves the wet strength of thewet wipe. Desirably, the wetting composition contains 5%-95% of awater-compatible organic solvent and 95%-5% water. A preferred organicsolvent is propylene glycol.

[0057] The wetting composition of the present invention may furthercomprise a variety of additives compatible with the water-compatibleorganic solvent and the water-dispersible binder, such that the strengthand dispersibility functions of the wipe are not jeopardized. Suitableadditives in the wetting composition include, but are not limited to,the following additives: skin-care additives; odor control agents;particulates; antimicrobial agents; preservatives; wetting agents andcleaning agents, such as detergents, surfactants, and some silicones;emollients; surface feel modifiers for improved tactile sensation (e.g.,lubricity) on the skin; fragrance; fragrance solubilizers; opacifiers;fluorescent whitening agents; UV absorbers; pharmaceuticals; and pHcontrol agents, such as malic acid or potassium hydroxide.

[0058] Skin-Care Additives

[0059] As used herein, the term “skin-care additives” representsadditives, which provide one or more benefits to the user, such as areduction in the probability of having diaper rash and/or other skindamage caused by fecal enzymes. These enzymes, particularly trypsin,chymotrypsin and elastase, are proteolytic enzymes produced in thegastrointestinal tract to digest food. In infants, for example, thefeces tend to be watery and contain, among other materials, bacteria,and some amounts of undegraded digestive enzymes. These enzymes, if theyremain in contact with the skin for any appreciable period of time, havebeen found to cause an irritation that is uncomfortable in itself andcan predispose the skin to infection by microorganisms. As acountermeasure, skin-care additives include, but are not limited to, theenzyme inhibitors and sequestrants set forth hereafter. The wettingcomposition may contain less than about 5 weight percent of skin-careadditives based on the total weight of the wetting composition. Morespecifically, the wetting composition may contain from about 0.01 weightpercent to about 2 weight percent of skin-care additives. Even morespecifically, the wetting composition may contain from about 0.01 weightpercent to about 0.05 weight percent of skin-care additives.

[0060] A variety of skin-care additives may be added to the wettingcomposition and the pre-moistened wipes of the present invention orincluded therein. In one embodiment of the present invention, skin-careadditives in the form of particles are added to serve as fecal enzymeinhibitors, offering potential benefits in the reduction of diaper rashand skin damage caused by fecal enzymes. U.S. Pat. No. 6,051,749, issuedApr. 18, 2000 to Schulz et al., the entirety of which is hereinincorporated by reference, discloses organophilic clays in a woven ornonwoven web, said to be useful for inhibiting fecal enzymes. Suchmaterials may be used in the present invention, including reactionproducts of a long chain organic quaternary ammonium compound with oneor more of the following clays: montmorillonite, bentonite, beidellite,hectorite, saponite, and stevensite.

[0061] Other known enzyme inhibitors and sequestrants may be used asskin-care additives in the wetting composition of the present invention,including those that inhibit trypsin and other digestive or fecalenzymes, and inhibitors for urease. For example, enzyme inhibitors andanti-microbial agents may be used to prevent the formation of odors inbody fluids. For example, urease inhibitors, which are also said to playa role in odor absorption, are disclosed by T. Trinh in World PatentApplication No. 98/26808, “Absorbent Articles with Odor Control System,”published Jun. 25, 1998, the entirety of which is herein incorporated byreference. Such inhibitors may be incorporated into the wettingcomposition and the pre-moistened wipes of the present invention andinclude transition metal ions and their soluble salts, such as silver,copper, zinc, ferric, and aluminum salts. The anion may also provideurease inhibition, such as borate, phytate, etc. Compounds of potentialvalue include, but are not limited to, silver chlorate, silver nitrate,mercury acetate, mercury chloride, mercury nitrate, copper metaborate,copper bromate, copper bromide, copper chloride, copper dichromate,copper nitrate, copper salicylate, copper sulfate, zinc acetate, zincborate, zinc phytate, zinc bromate, zinc bromide, zinc chlorate, zincchloride, zinc sulfate, cadmium acetate, cadmium borate, cadmiumbromide, cadmium chlorate, cadmium chloride, cadmium formate, cadmiumiodate, cadmium iodide, cadmium permanganate, cadmium nitrate, cadmiumsulfate, and gold chloride.

[0062] Other salts that have been disclosed as having urease inhibitionproperties include ferric and aluminum salts, especially the nitrates,and bismuth salts. Other urease inhibitors are disclosed by Trinh,including hydroxamic acid and its derivatives; thiourea; hydroxylamine;salts of phytic acid; extracts of plants of various species, includingvarious tannins, e.g. carob tannin, and their derivatives such aschlorogenic acid derivatives; naturally occurring acids such as ascorbicacid, citric acid, and their salts; phenyl phosphoro diamidate/diaminophosphoric acid phenyl ester; metal aryl phosphoramidate complexes,including substituted phosphorodiamidate compounds; phosphoramidateswithout substitution on the nitrogen; boric acid and/or its salts,including especially, borax, and/or organic boron acid compounds; thecompounds disclosed in European Patent Application 408,199; sodium,copper, manganese, and/or zinc dithiocarbamate; quinones; phenols;thiurams; substituted rhodanine acetic acids; alkylated benzoquinones;formarnidine disulphide; 1:3-diketones maleic anhydride; succinamide;phthalic anhydride; pehenic acid; /N,N-dihalo-2-imidazolidinones;N-halo2-oxazolidinones; thio- and/or acyl-phosphoryltnamide and/orsubstituted derivatives thereof-, thiopyridine-N-oxides, thiopyridines,and thiopyrimidines; oxidized sulfur derivatives of diarninophosphinylcompounds; cyclotriphosphazatriene derivatives; ortho-diaminophosphinylderivatives of oximes; bromo-nitro compounds; S-aryl and/or alkyldiamidophosphorothiolates; diaminophosphinyl derivatives; mono- and/orpolyphosphorodiamide; 5-substituted-benzoxathiol-2-ones;N(diaminophosphinyl)arylcarboxamides; alkoxy-1,2-benzothaizin compounds;etc.

[0063] Many other skin-care additives may be incorporated into thewetting composition and pre-moistened wipes of the present invention,including, but not limited to, sun blocking agents and UV absorbers,acne treatments, pharmaceuticals, baking soda (including encapsulatedforms thereof), vitamins and their derivatives such as Vitamins A or E,botanicals such as witch hazel extract and aloe vera, allantoin,emollients, disinfectants, hydroxy acids for wrinkle control oranti-aging effects, sunscreens, tanning promoters, skin lighteners,deodorants and anti-perspirants, ceramides for skin benefits and otheruses, astringents, moisturizers, nail polish removers, insectrepellants, antioxidants, antiseptics, anti-inflammatory agents and thelike, provided that the additives are compatible with an bindercomposition associated therewith, and especially the binder compositionsof the present invention (i.e., they do not cause a substantial loss ofstrength in the wet state of the pre-moistened wipes, prior to dilutionin water, while permitting dispersibility in water).

[0064] Useful materials for skin care and other benefits are listed inMcCutcheon's 1999, Vol. 2: Functional Materials, MC Publishing Company,Glen Rock, N.J. Many useful botanicals for skin care are provided byActive Organics, Lewisville, Tex.

[0065] Odor Control Additives

[0066] Suitable odor control additives for use in the wettingcomposition and pre-moistened wipes of the present invention include,but are not limited to, zinc salts; talc powder; encapsulated perfumes(including microcapsules, macrocapsules, and perfume encapsulated inliposomes, vessicles, or microemulsions); chelants, such asethylenediamine tetra-acetic acid; zeolites; activated silica, activatedcarbon granules or fibers; activated silica particulates; polycarboxylicacids, such as citric acid; cyclodextrins and cyclodextrin derivatives;chitosan or chitin and derivatives thereof; oxidizing agents;antimicrobial agents, including silver-loaded zeolites (e.g., those ofBF Technologies, located in Beverly, Mass., sold under the trademarkHEALTHSHIELD™; triclosan; kieselguhr; and mixtures thereof. In additionto controlling odor from the body or body wastes, odor controlstrategies can also be employed to mask or control any odor of thetreated substrate. Desirably, the wetting composition contains less thanabout 5 weight percent of odor control additives based on the totalweight of the wetting composition. More desirably, the wettingcomposition contains from about 0.01 weight percent to about 2 weightpercent of odor control additives. Even more desirably, the wettingcomposition contains from about 0.03 weight percent to about 1 weightpercent of odor control additives.

[0067] In one embodiment of the present invention, the wettingcomposition and/or pre-moistened wipes comprise derivatizedcyclodextrins, such as hydroxypropyl beta-cyclodextrin in solution,which remain on the skin after wiping and provide an odor-absorbinglayer. In other embodiments, the odor source is removed or neutralizedby application of an odor-control additive, exemplified by the action ofa chelant that binds metal groups necessary for the function of manyproteases and other enzymes that commonly produce an odor. Chelating themetal group interferes with the enzyme's action and decreases the riskof malodor in the product.

[0068] Principles for the application of chitosan or chitin derivativesto nonwoven webs and cellulosic fibers are described by S. Lee et al. in“Antimicrobial and Blood Repellent Finishes for Cotton and NonwovenFabrics Based on Chitosan and Fluoropolymers,” Textile Research Journal,69(2); 104-112, Feb. 1999.

[0069] Detackifying Agents

[0070] While elevated salt concentrations may reduce the tack of thebinder, other means of tack reduction are often desirable. Thus,detackifying agents may be used in the wetting composition to reduce thetackiness, if any, of the binder. Suitable detackifiers include anysubstance known in the art to reduce tack between two adjacent fibroussheets treated with an adhesive-like polymer or any substance capable ofreducing the tacky feel of an adhesive like polymer on the skin.Detackifiers may be applied as solid particles in dry form, as asuspension or as a slurry of particles. Deposition may be by spray,coating, electrostatic deposition, impingement, filtration (i.e, apressure differential drives a particle-laden gas phase through thesubstrate, depositing particles by a filtration mechanism), and thelike, and may be applied uniformly on one or more surfaces of thesubstrate or may be applied in a pattern (e.g., repeating or randompatterns) over a portion of the surface or surfaces of the substrate.The detackifier may be present throughout the thickness of thesubstrate, but may be concentrated at one or both surfaces, and may besubstantially only present on one or both surfaces of the substrate.

[0071] Specific detackifiers include, but are not limited to, powders,such as talc powder, calcium carbonate, mica; starches, such as cornstarch; lycopodium powder; mineral fillers, such as titanium dioxide;silica powder; alumina; metal oxides in general; baking powder;kieselguhr; and the like. Polymers and other additives having lowsurface energy may also be used, including a wide variety of fluorinatedpolymers, silicone additives, polyolefins and thermoplastics, waxes,debonding agents known in the paper industry including compounds havingalkyl side chains such as those having 16 or more carbons, and the like.Compounds used as release agents for molds and candle making may also beconsidered, as well as, dry lubricants and fluorinated release agents.

[0072] In one embodiment, the detackifier comprisespolytetrafluorethylene (PTFE), such as PTFE telomer (KRYTOX® DF)compound, used in the PTFE release agent dry lubricant MS122DF, marketedby Miller-Stephenson (Danbury, Conn.) as a spray product. For example,PTFE particles may be applied by spray to one side of the substrateprior to winding of the pre-moistened wipes. In one embodiment, adetackifying agent is applied to only one surface of the substrate priorto winding into a roll.

[0073] The wetting composition desirably contains less than about 25weight percent of detackifying agents based on the total weight of thewetting composition. More desirably, the wetting composition containsfrom about 0.01 weight percent to about 10 weight percent ofdetackifying agents, more specifically about 5% or less. Even morespecifically, the wetting composition contains from about 0.05 weightpercent to about 2 weight percent of detackifying agents.

[0074] In addition to acting as a detackifying agent, starch compoundsmay also improve the strength properties of the pre-moistened wipes. Forexample, it has been found that ungelled starch particles, such ashydrophilic tapioca starch, when present at a level of about 1% orhigher by weight relative to the weight of the wetting compositionimproves wet strength. Starch may be applied by adding the starch to asuspension of laponite to improve the dispersion of the starch withinthe wetting composition.

[0075] Microparticulates

[0076] The wetting composition of the present invention may be furthermodified by the addition of solid particulates or microparticulates.Suitable particulates include, but are not limited to, mica, silica,alumina, calcium carbonate, kaolin, talc, and zeolites. The particulatesmay be treated with stearic acid or other additives to enhance theattraction or bridging of the particulates to the binder system, ifdesired. Also, two-component microparticulate systems, commonly used asretention aids in the papermaking industry, may also be used. Suchtwo-component microparticulate systems generally comprise a colloidalparticle phase, such as silica particles, and a water-soluble cationicpolymer for bridging the particles to the fibers of the web to beformed. The presence of particulates in the wetting composition canserve one or more useful functions, such as (1) increasing the opacityof the pre-moistened wipes; (2) modifying the rheology or reducing thetackiness of the pre-moistened wipe; (3) improving the tactileproperties of the wipe; or (4) delivering desired agents to the skin viaa particulate carrier, such as a porous carrier or a microcapsule.Desirably, the wetting composition contains less than about 25 weightpercent of particulate based on the total weight of the wettingcomposition. More specifically, the wetting composition may contain fromabout 0.05 weight percent to about 10 weight percent ofmicroparticulate. Even more specifically, the wetting composition maycontain from about 0.1 weight percent to about 5 weight percent ofmicroparticulate.

[0077] Microcapsules and Other Delivery Vehicles

[0078] Microcapsules and other delivery vehicles may also be used in thewetting composition of the present invention to provide skin-careagents; medications; comfort promoting agents, such as eucalyptus;perfumes; skin care agents; odor control additives; vitamins; powders;and other additives to the skin of the user. Specifically, the wettingcomposition may contain up to about 25 weight percent of microcapsulesor other delivery vehicles based on the total weight of the wettingcomposition. More specifically, the wetting composition may contain fromabout 0.05 weight percent to about 10 weight percent of microcapsules orother delivery vehicles. Even more specifically, the wetting compositionmay contain from about 0.2 weight percent to about 5.0 weight percent ofmicrocapsules or other delivery vehicles.

[0079] Microcapsules and other delivery vehicles are well known in theart. For example, POLY-PORE® E200 (Chemdal Corp., Arlington Heights,Ill.), is a delivery agent comprising soft, hollow spheres that cancontain an additive at over 10 times the weight of the delivery vehicle.Known additives reported to have been used with POLY-PORE® E200 include,but are not limited to, benzoyl peroxide, salicylic aid, retinol,retinyl palmitate, octyl methoxycinnamate, tocopherol, siliconecompounds (DC 435), and mineral oil. Another useful delivery vehicle isa sponge-like material marketed as POLY-PORE® L200, which is reported tohave been used with silicone (DC 435) and mineral oil. Other knowndelivery systems include cyclodextrins and their derivatives, liposomes,polymeric sponges, and spray-dried starch.

[0080] Additives present in microcapsules are isolated from theenvironment and the other agents in the wetting composition until thewipe is applied to the skin, whereupon the microcapsules break anddeliver their load to the skin or other surfaces.

[0081] Preservatives and Anti-Microbial Agents

[0082] The wetting composition of the present invention may also containpreservatives and/or anti-microbial agents. Several preservatives and/oranti-microbial agents, such as Mackstat H 66 (available from McIntyreGroup, Chicago, Ill.), have been found to give excellent results inpreventing bacteria and mold growth. Other suitable preservatives andanti-microbial agents include, but are not limited to DMDM hydantoin(e.g., Glydant Plus™, Lonza, Inc., Fair Lawn, N.J.), iodopropynylbutylcarbamate, Kathon (Rohm and Hass, Philadelphia, Pa.),methylparaben, propylparaben, 2-bromo-2-nitropropane-1,3-diol, benzoicacid, and the like. Desirably, the wetting composition contains lessthan about 2 weight percent on an active basis of preservatives and/oranti-microbial agents based on the total weight of the wettingcomposition. More desirably, the wetting composition contains from about0.01 weight percent to about 1 weight percent of preservatives and/oranti-microbial agents. Even more desirably, the wetting compositioncontains from about 0.01 weight percent to about 0.5 weight percent ofpreservatives and/or anti-microbial agents.

[0083] Wetting Agents and Cleaning Agents

[0084] A variety of wetting agents and/or cleaning agents may be used inthe wetting composition of the present invention. Suitable wettingagents and/or cleaning agents include, but are not limited to,detergents and nonionic, amphoteric, and anionic surfactants, especiallyamino acid-based surfactants. Amino acid-based surfactant systems, suchas those derived from amino acids L-glutamic acid and other naturalfatty acids, offer pH compatibility to human skin and good cleansingpower, while being relatively safe and providing improved tactile andmoisturization properties compared to other anionic surfactants. Onefunction of the surfactant is to improve wetting of the dry substratewith the wetting composition. Another function of the surfactant can beto disperse bathroom soils when the pre-moistened wipe contacts a soiledarea and to enhance their absorption into the substrate. The surfactantcan further assist in make-up removal, general personal cleansing, hardsurface cleansing, odor control, and the like.

[0085] One commercial example of an amino-acid based surfactant isacylglutamate, marketed under the Amisoft name by Ajinomoto Corp.,Tokyo, Japan. Desirably, the wetting composition contains less thanabout 3 weight percent of wetting agents and/or cleaning agents based onthe total weight of the wetting composition. More desirably, the wettingcomposition contains from about 0.01 weight percent to about 2 weightpercent of wetting agents and/or cleaning agents. Even more desirably,the wetting composition contains from about 0.1 weight percent to about0.5 weight percent of wetting agents and/or cleaning agents.

[0086] Although amino-acid based surfactants are particularly useful inthe wetting compositions of the present invention, a wide variety ofsurfactants may be used in the present invention. Suitable non-ionicsurfactants include, but are not limited to, the condensation productsof ethylene oxide with a hydrophobic (oleophilic) polyoxyalkylene baseformed by the condensation of propylene oxide with propylene glycol. Thehydrophobic portion of these compounds desirably has a molecular weightsufficiently high so as to render it water-insoluble. The addition ofpolyoxyethylene moieties to this hydrophobic portion increases thewater-solubility of the molecule as a whole, and the liquid character ofthe product is retained up to the point where the polyoxyethylenecontent is about 50% of the total weight of the condensation product.Examples of compounds of this type include commercially-availablePluronic surfactants (BASF Wyandotte Corp.), especially those in whichthe polyoxypropylene ether has a molecular weight of about 1500-3000 andthe polyoxyethylene content is about 35-55% of the molecule by weight,i.e. Pluronic L-62.

[0087] Other useful nonionic surfactants include, but are not limitedto, the condensation products of C₈-C₂₂ alkyl alcohols with 2-50 molesof ethylene oxide per mole of alcohol. Examples of compounds of thistype include the condensation products of C₁₁-C₁₅ secondary alkylalcohols with 3-50 moles of ethylene oxide per mole of alcohol, whichare commercially-available as the Poly-Tergent SLF series from OlinChemicals or the TERGITOL™ series from Union Carbide, i.e. TERGITOL™25-L-7, which is formed by condensing about 7 moles of ethylene oxidewith a C₁₂-C₁₅ alkanol.

[0088] Other nonionic surfactants, which may be employed in the wettingcomposition of the present invention, include the ethylene oxide estersof C₆-C₁₂ alkyl phenols such as (nonylphenoxy)polyoxyethylene ether.Particularly useful are the esters prepared by condensing about 8-12moles of ethylene oxide with nonylphenol, i.e. the IGEPAL® CO series(GAF Corp.).

[0089] Further non-ionic surface active agents include, but are notlimited to, alkyl polyglycosides (APG), derived as a condensationproduct of dextrose (D-glucose) and a straight or branched chainalcohol. The glycoside portion of the surfactant provides a hydrophilehaving high hydroxyl density, which enhances water solubility.Additionally, the inherent stability of the acetal linkage of theglycoside provides chemical stability in alkaline systems. Furthermore,unlike some non-ionic surface active agents, alkyl polyglycosides haveno cloud point, allowing one to formulate without a hydrotrope, andthese are very mild, as well as readily biodegradable non-ionicsurfactants. This class of surfactants is available from HorizonChemical under the trade names of APG-300, APG-350, APG-500, andAPG-500.

[0090] Silicones are another class of wetting agents available in pureform, or as microemulsions, macroemulsions, and the like. One exemplarynon-ionic surfactant group is the silicone-glycol copolymers. Thesesurfactants are prepared by adding poly(lower)alkylenoxy chains to thefree hydroxyl groups of dimethylpolysiloxanols and are available fromthe Dow Coming Corp as Dow Coming 190 and 193 surfactants (CTFA name:dimethicone copolyol). These surfactants function, with or without anyvolatile silicones used as solvents, to control foaming produced by theother surfactants, and also impart a shine to metallic, ceramic, andglass surfaces.

[0091] Anionic surfactants may also be used in the wetting compositionsof the present invention. Anionic surfactants are useful due to theirhigh detergency include anionic detergent salts having alkylsubstituents of 8 to 22 carbon atoms such as the water-soluble higherfatty acid alkali metal soaps, e.g., sodium myristate and sodiumpalmitate. A preferred class of anionic surfactants encompasses thewater-soluble sulfated and sulfonated anionic alkali metal and alkalineearth metal detergent salts containing a hydrophobic higher alkyl moiety(typically containing from about 8 to 22 carbon atoms) such as salts ofhigher alkyl mono or polynuclear aryl sulfonates having from about 1 to16 carbon atoms in the alkyl group, with examples available as theBio-Soft series, i.e. Bio-Soft D-40 (Stepan Chemical Co.).

[0092] Other useful classes of anionic surfactants include, but are notlimited to, the alkali metal salts of alkyl naphthalene sulfonic acids(methyl naphthalene sodium sulfonate, Petro AA, PetrochemicalCorporation); sulfated higher fatty acid monoglycerides such as thesodium salt of the sulfated monoglyceride of cocoa oil fatty acids andthe potassium salt of the sulfated monoglyceride of tallow fatty acids;alkali metal salts of sulfated fatty alcohols containing from about 10to 18 carbon atoms (e.g., sodium lauryl sulfate and sodium stearylsulfate); sodium C₁₄-C₁₆-alphaolefin sulfonates such as the Bio-Tergeseries (Stepan Chemical Co.); alkali metal salts of sulfated ethyleneoxyfatty alcohols (the sodium or ammonium sulfates of the condensationproducts of about 3 moles of ethylene oxide with a C₁₂-C₁₅ n-alkanol,i.e., the Neodol ethoxysulfates, Shell Chemical Co.); alkali metal saltsof higher fatty esters of low molecular weight alkylol sulfonic acids,e.g. fatty acid esters of the sodium salt of isothionic acid, the fattyethanolamide sulfates; the fatty acid amides of amino alkyl sulfonicacids, e.g. lauric acid amide of taurine; as well as numerous otheranionic organic surface active agents such as sodium xylene sulfonate,sodium naphthalene sulfonate, sodium toulene sulfonate and mixturesthereof.

[0093] A further useful class of anionic surfactants includes the8-(4-n-alkyl-2-cyclohexenyl)-octanoic acids, wherein the cyclohexenylring is substituted with an additional carboxylic acid group. Thesecompounds or their potassium salts, are commercially-available fromWestvaco Corporation as Diacid 1550 or H-240. In general, these anionicsurface active agents can be employed in the form of their alkali metalsalts, ammonium or alkaline earth metal salts.

[0094] Macroemulsions and Microemulsion of Silicone Particles

[0095] The wetting composition may further comprise an aqueousmicroemulsion of silicone particles. For example, U.S. Pat. No.6,037,407, “Process for the Preparation of Aqueous Emulsions of SiliconeOils and/or Gums and/or Resins” issued Mar. 14, 2000, disclosesorganopolysiloxanes in an aqueous microemulsion. Desirably, the wettingcomposition contains less than about 5 weight percent of a microemulsionof silicone particles based on the total weight of the wettingcomposition. More desirably, the wetting composition contains from about0.02 weight percent to about 3 weight percent of a microemulsion ofsilicone particles. Even more desirably, the wetting compositioncontains from about 0.02 weight percent to about 0.5 weight percent of amicroemulsion of silicone particles.

[0096] Silicone emulsions in general may be applied to the pre-moistenedwipe by any known coating method. For example, the pre-moistened wipemay be moistened with an aqueous composition comprising awater-dispersible or water-miscible, silicone-based component that iscompatible with the activating compound in the wetting composition.Further, the wipe can comprise a nonwoven web of fibers having awater-dispersible binder, wherein the web is moistened with a lotioncomprising a silicone based sulfosuccinate. The silicone-basedsulfosuccinate provides gentle and effective cleansing without a highlevel of surfactant. Additionally, the silicone-based sulfosuccinateprovides a solubilization function, which prevents precipitation ofoil-soluble components, such as fragrance components, vitamin extracts,plant extracts, and essential oils.

[0097] In one embodiment of the present invention, the wettingcomposition comprises a silicone copolyol sulfosuccinate, such asdisodium dimethicone copolyol sulfosuccinate and diammonium dimethiconecopolyolsulfosuccinate. Desirably, the wetting composition comprisesless than about 2 percent by weight of the silicone-basedsulfosuccinate, and more desirably from about 0.05 percent to about 0.30percent by weight of the silicone-based sulfosuccinate.

[0098] In another example of a product comprising a silicone emulsions,Dow Coming 9506 powder may also be present in the wetting composition.Dow Coming 9506 powder is believed to comprise adimethicone/vinyldimethicone cross-polymer and is a spherical powder,which is said to be useful in controlling skin oils (see “New ChemicalPerspectives,” Soap and Cosmetics, Vol. 76, No. 3, Mar. 2000, p. 12).Thus, a water-dispersible wipe, which delivers a powder effective incontrolling skin oil, is also within the scope of the present invention.Principles for preparing silicone emulsions are disclosed in WO97/10100, published Mar. 20, 1997.

[0099] Emollients

[0100] The wetting composition of the present invention may also containone or more emollients. Suitable emollients include, but are not limitedto, PEG 75 lanolin, methyl gluceth 20 benzoate, C₁₂-C₁₅ alkyl benzoate,ethoxylated cetyl stearyl alcohol, products marketed as Lambent waxWS-L, Lambent WD-F, Cetiol HE (Henkel Corp.), Glucam P20 (Amerchol),Polyox WSR N-10 (Union Carbide), Polyox WSR N-3000 (Union Carbide),Luviquat (BASF), Finsolv SLB 101 (Finetex Corp.), mink oil, allantoin,stearyl alcohol, Estol 1517 (Unichema), and Finsolv SLB 201 (FinetexCorp.).

[0101] An emollient can also be applied to a surface of the articleprior to or after wetting with the wetting composition. Such anemollient may be insoluble in the wetting composition and can beimmobile except when exposed to a force. For example, a petrolatum-basedemollient can be applied to one surface in a pattern, after which theother surface is wetted to saturate the wipe. Such a product couldprovide a cleaning surface and an opposing skin treatment surface.

[0102] The emollient composition in such products and other products ofthe present invention can comprise a plastic or fluid emollient such asone or more liquid hydrocarbons (e.g., petrolatum), mineral oil and thelike, vegetable and animal fats (e.g., lanolin, phospholipids and theirderivatives) and/or a silicone materials such as one or more alkylsubstituted polysiloxane polymers, including the polysiloxane emollientsdisclosed in U.S. Pat. No. 5,891,126, issued Apr. 6, 1999 to Osborn, IIIet al. Optionally, a hydrophilic surfactant may be combined with aplastic emollient to improve wettability of the coated surface. In someembodiments of the present invention, it is contemplated that liquidhydrocarbon emollients and/or alkyl substituted polysiloxane polymersmay be blended or combined with one or more fatty acid ester emollientsderived from fatty acids or fatty alcohols.

[0103] In an embodiment of the present invention, the emollient materialis in the form of an emollient blend. Desirably, the emollient blendcomprises a combination of one or more liquid hydrocarbons (e.g.,petrolatum), mineral oil and the like, vegetable and animal fats (e.g.,lanolin, phospholipids and their derivatives), with a silicone materialsuch as one or more alkyl substituted polysiloxane polymers. Moredesirably, the emollient blend comprises a combination of liquidhydrocarbons (e.g., petrolatum) with dimethicone or with dimethicone andother alkyl substituted polysiloxane polymers. In some embodiments ofthe present invention, it is contemplated that blends of liquidhydrocarbon emollients and/or alkyl substituted polysiloxane polymersmay be blended with one or more fatty acid ester emollients derived fromfatty acids or fatty alcohols. PEG-7 glyceryl cocoate, available asStandamul HE (Henkel Corp., Hoboken, N.J.), can also be considered.

[0104] Water-soluble, self-emulsifying emollient oils, which are usefulin the present wetting compositions, include the polyoxyalkoxylatedlanolins and the polyoxyalkoxylated fatty alcohols, as disclosed in U.S.Pat. No. 4,690,821, issued Sep. 1, 1987 to Smith et al. Thepolyoxyalkoxy chains desirably will comprise mixed propylenoxy andethyleneoxy units. The lanolin derivatives will typically comprise about20-70 such lower-alkoxy units while the C₁₂-C₂₀-fatty alcohols will bederivatized with about 8-15 lower-alkyl units. One such useful lanolinderivative is Lanexol AWS (PPG-12-PEG-50, Croda, Inc., New York, N.Y.).A useful poly(15-20) C₂-C₃-alkoxylate is PPG-5-Ceteth-20, known asProcetyl AWS (Croda, Inc.).

[0105] According to one embodiment of the present invention, theemollient material reduces undesirable tactile attributes, if any, ofthe wetting composition. For example, emollient materials, includingdimethicone, can reduce the level of tackiness that may be caused by thebinder or other components in the wetting composition, thus serving as adetackifier.

[0106] Desirably, the wetting composition contains less than about 25weight percent of emollients based on the total weight of the wettingcomposition. More specifically, the wetting composition may compriseless than about 5 weight percent emollient, and most specifically lessthan about 2% emollient. More desirably, the wetting composition maycontain from about 0.01 weight percent to about 8 weight percent ofemollients. Even more desirably, the wetting composition may containfrom about 0.2 weight percent to about 2 weight percent of emollients.

[0107] In one embodiment, the wetting composition and/or pre-moistenedwipes of the present invention comprise an oil-in-water emulsioncomprising an oil phase containing at least one emollient oil and atleast one emollient wax stabilizer dispersed in an aqueous phasecomprising at least one polyhydric alcohol emollient and at least oneorganic water-soluble detergent, as disclosed in U.S. Pat. No.4,559,157, issued Dec. 17, 1985 to Smith et al., the entirety of whichis herein incorporated by reference.

[0108] Surface Feel Modifiers

[0109] Surface feel modifiers are used to improve the tactile sensation(e.g., lubricity) of the skin during use of the product. Suitablesurface feel modifiers include, but are not limited to, commercialdebonders; and softeners, such as the softeners used in the art oftissue making including quaternary ammonium compounds with fatty acidside groups, silicones, waxes, and the like. Exemplary quaternaryammonium compounds with utility as softeners are disclosed in U.S. Pat.No. 3,554,862, issued to Hervey et al. on Jan. 12, 1971; U.S. Pat. No.4,144,122, issued to Emanuelsson et al., Mar. 13, 1979, U.S. Pat. No.5,573,637, issued to Ampulski et al. Nov. 12, 1996; and U.S. Pat. No.4,476,323, issued to Hellsten et al., Oct. 9, 1984, the entirety of allof which is herein incorporated by reference. Desirably, the wettingcomposition contains less than about 2 weight percent of surface feelmodifiers based on the total weight of the wetting composition. Moredesirably, the wetting composition contains from about 0.01 weightpercent to about 1 weight percent of surface feel modifiers. Even moredesirably, the wetting composition contains from about 0.01 weightpercent to about 0.05 weight percent of surface feel modifiers.

[0110] Fragrances

[0111] A variety of fragrances may be used in the wetting composition ofthe present invention. Desirably, the wetting composition contains lessthan about 2 weight percent of fragrances based on the total weight ofthe wetting composition. More desirably, the wetting compositioncontains from about 0.01 weight percent to about 1 weight percent offragrances. Even more desirably, the wetting composition contains fromabout 0.01 weight percent to about 0.05 weight percent of fragrances.

[0112] Fragrance Solubilizers

[0113] Further, a variety of fragrance solubilizers may be used in thewetting composition of the present invention. Suitable fragrancesolubilizers include, but are not limited to, polysorbate 20, propyleneglycol, ethanol, isopropanol, diethylene glycol monoethyl ether,dipropylene glycol, diethyl phthalate, triethyl citrate, Ameroxol OE-2(Amerchol Corp.), Brij 78 and Brij 98 (ICI Surfactants), Arlasolve 200(ICI Surfactants), Calfax 16L-35 (Pilot Chemical Co.), Capmul POE-S(Abitec Corp.), Finsolv SUBSTANTIAL (Finetex), and the like. Desirably,the wetting composition contains less than about 2 weight percent offragrance solubilizers based on the total weight of the wettingcomposition. More desirably, the wetting composition contains from about0.01 weight percent to about 1 weight percent of fragrance solubilizers.Even more desirably, the wetting composition contains from about 0.01weight percent to about 0.05 weight percent of fragrance solubilizers.

[0114] Opacifiers

[0115] Suitable opacifiers include, but are not limited to, titaniumdioxide or other minerals or pigments, and synthetic opacifiers such asREACTOPAQUE® particles (available from Sequa Chemicals, Inc., Chester,S.C.). Desirably, the wetting composition contains less than about 2weight percent of opacifiers based on the total weight of the wettingcomposition. More desirably, the wetting composition contains from about0.01 weight percent to about 1 weight percent of opacifiers. Even moredesirably, the wetting composition contains from about 0.01 weightpercent to about 0.05 weight percent of opacifiers.

[0116] pH Control Agents

[0117] Suitable pH control agents for use in the wetting composition ofthe present invention include, but are not limited to, malic acid,citric acid, hydrochloric acid, acetic acid, sodium hydroxide, potassiumhydroxide, and the like. An appropriate pH range minimizes the amount ofskin irritation resulting from the wetting composition on the skin.Desirably, the pH range of the wetting composition is from about 3.5 toabout 6.5. More desirably, the pH range of the wetting composition isfrom about 4 to about 6. Desirably, the wetting composition containsless than about 2 weight percent of a pH adjuster based on the totalweight of the wetting composition. More desirably, the wettingcomposition contains from about 0.01 weight percent to about 1 weightpercent of a pH adjuster. Even more desirably, the wetting compositioncontains from about 0.01 weight percent to about 0.05 weight percent ofa pH adjuster.

[0118] Although a variety of wetting compositions, formed from one ormore of the above-described components, may be used with the wet wipesof the present invention, in one embodiment, the wetting compositioncontains the following components, given in weight percent of thewetting composition, as shown in Table 2 below: TABLE 2 WettingComposition Components Wetting Composition Component: Weight Percent:Deionized Water about 86 to about 98 Organic Solvent about 5 to about 20Preservative Up to about 2 Surtactant Up to about 2 Silicone Emulsion Upto about 1 Emollient Up to about 1 Fragrance Up to about 0.3 Fragrancesolubilizer Up to about 0.5 pH adjuster Up to about 0.2

[0119] In another embodiment of the present invention, the wettingcomposition comprises the following components, given in weight percentof the wetting composition, as shown in Table 3 below: TABLE 3 WettingComposition Components Class of Wetting Specific Wetting CompositionComposition Component Weight Component: Component: Name: Percent:Vehicle Deionized Water about 86 to about 98 Organic Solvent Propyleneglycol about 5 to about 20 Preservative Glycerin, IPBC Mackstat H-66 Upto about 2 and DMDM (McIntyre Group, Hydantoin Chicago, IL) SurfactantAcyl Glutamate CS22 Up to about 2 (Ajinomoto, Tokyo, Japan) SiliconeEmulsion Dimethiconol DC1785 Up to about 1 (Detackifier/ and TEA (DowCorning, Skin Feel agent) Dodecylbenezene Midland, MI) SulfonateEmollient PEG-75 Lanolin Solulan L-575 Up to about 1 (Amerchol,Middlesex, NJ) Fragrance Fragrance Dragoco Up to about 0.3 0/708768(Dragoco, Roseville, MN) Fragrance Polysorbate 20 Glennsurf L20 Up toabout 0.5 solubilizer (Glenn Corp., St. Paul, MN) pH adjuster Malic Acidto Up to about 0.2 pH 5 (Haarman & Reimer, Teterboro, NJ)

[0120] In another embodiment of the present invention, the wettingcomposition comprises the following components, given in weight percentof the wetting composition, as shown in Table 4 below: TABLE 4 AnExemplary Wetting Composition Class of Wetting Specific Wettingcomposition composition Component Component: Component: Name: WeightPercent: Vehicle Deionized Water about 93 Organic Solvent Propyleneglycol about 20 Preservative Glycerin, IPBC Mackstat about 1 and DMDMH-66 Hydantoin Surfactant Acyl Glutamate CS22/ECS about 1 22P SiliconeDimethiconol DC1784/ about 0.5 Emulsion and TEA DC1785 DodecylbenezeneSulfonate Emollient PEG-75 Lanolin Solulan L-575 about 0.25 FragranceFragrance Dragoco about 0.05 Fragrance 0/708768 Fragrance Polysorbate 20Glennsurf L20 about 0.25 solubilizer pH adjuster Malic Acid to about0.07 pH 5

[0121] It should be noted that the above-described wetting compositionsof the present invention may be used with any one of the above describedbinder compositions of the present invention. Further, the abovedescribed wetting compositions of the present invention may be used withany other binder composition, including conventional bindercompositions, or with any known fibrous or absorbent substrate, whetherdispersible or not.

[0122] Strength Properties

[0123] Unless otherwise specified, tensile testing is performedaccording to the following protocol. Testing of dry product should beconducted under Tappi conditions (50% relative humidity, 73° F.) with aprocedure similar to ASTM-1117-80, section 7. Tensile tests areperformed with a constant crosshead speed tensile tester such as theThwing Albert 1256-100 tensile tester with an RSA-210-kg load cell.Specimens are cut to 3-inch widths and 6 inch lengths, and mountedbetween jaws with a 4-inch gauge length. The crosshead speed is 12inches per minute. Peak load (for tensile strength) and elongation atpeak load (for stretch) are measured. For cross direction (CD) tensiletests, the sample is cut in the cross direction. For machine direction(MD) tensile tests, the sample is cut in the cross direction.

[0124] Tensile tests in the dry state are reported for webs taken priorto application of the wetting composition. The machine direction drytensile strength is abbreviated as “MDDT,” and the cross direction drytensile strength as “CDDT.” The results can be reported as kg/3-in orconverted to units of g/in or g/2.54 cm.

[0125] Based on the dry weight of the specimen cut to the appropriatesize, an excess amount of wetting solution (4% saline solution with noother additives, unless otherwise specified) is applied to reach asolution add-on of 250-400%. The wetted specimens are then immediatelypassed through an Atlas Lab Wringer (Atlas Electric Devices Company,Chicago, Ill. No. 10404 LW-1, no load) to uniformly distribute thesolution in the sample and gently remove the excess solution to achievea final solution add-on of 200%. Several iterations or passes may beneeded to reach the add-on target depending on the sample. Thecompleted, pre-moistened samples are then bagged in plastic to preventdry-out before testing.

[0126] Cross direction wet tensile tests (CDWT) or machine direction wettensile strength (MDWT) are performed as described above using thepre-moistened sample as is, after the sample has equilibrated by sittingovernight in a sealed plastic bag.

[0127] For tests related to strength loss in a pre-moistened weboccurring after exposure to a new solution, a container havingdimensions of 200 mm by 120 mm and deep enough to hold 1000 ml is filledwith 700 ml of the selected soak solution. No more than 108 squareinches of sample are soaked in the 700 ml of soaking solution, dependingon specimen size. The pre-moistened specimens, that have equilibratedovernight, are immersed in the soak solution and then allowed to soakundisturbed for a specified time period (typically 1 hour). At thecompletion of the soak period, samples are carefully retrieved from thesoak solution, allowed to drain, and then tested immediately asdescribed above (i.e., the sample is immediately mounted in the tensiletester and tested, without being passed through the wringer). In caseswith highly dispersible materials, the samples often cannot be retrievedfrom the soaking solution without falling apart. The soaked tensilevalues for such samples are recorded as zero for the correspondingsolution.

[0128] For the deionized soaked cross-direction wet tensile test,S-CDWT, the sample is immersed in deionized water for 1 hour and thentested. For the hard-water soaked cross-direction wet tensile test,S-CDWT-M (M indicating divalent metal ions), the sample is immersed inwater containing 200 ppm of Ca⁺⁺/Mg⁺⁺ in a 2:1 ratio prepared fromcalcium chloride and magnesium chloride, soaked for one hour and thentested. For the medium hard water soaked cross-direction wet tensiletest, MS-CDWT-M, the sample is immersed in water containing 50 ppm ofCa⁺⁺/Mg⁺⁺ in a 2:1 ratio, soaked for one hour and then tested. Testingdone with other time increments or soaking solutions should be soindicated to prevent confusion with the S-CDWT or S-CDWT-M tests.

[0129] The amount of wetting composition added to the nonwoven fabric,relative to the weight of the dry nonwoven fabric in the presentinvention, is desirably about 180 percent to about 240 weight percent.

[0130] Desirably, the wet wipes of the present invention possess anin-use wet tensile strength (CDWT) of at least 100 g/in, and a tensilestrength of less than about 30 g/in after being soaked in water having aconcentration of Ca² ⁺ and/or Mg² ⁺ ions of about 50 ppm for about onehour (MS-CDWT-M). More desirably, the wet wipes possess an in-use wettensile strength of at least 300 g/in (CDWT), and a tensile strength ofless than about 30 g/in after being soaked in water having aconcentration of Ca² ⁺ and/or Mg²⁺ ions of about 50 ppm for about onehour (MS-CDWT-M). In a further embodiment, the wet wipes desirablypossess an in-use wet tensile strength of at least 200 g/in (CDWT), anda tensile strength of less than about 20 g/in after being soaked inwater having a concentration of Ca²⁺ and/or Mg² ⁺ ions of about 200 ppmfor about one hour (S-CDWT-M). Even more desirably, the wet wipespossess an in-use wet tensile strength of at least 300 g/in, and atensile strength of less than about 20 g/in after being soaked in waterhaving a concentration of Ca² ⁺ and/or Mg² ⁺ ions of about 200 ppm forabout one hour (S-CDWT-M).

[0131] Products with high basis weights or wet strengths than flushablewet wipes may have relatively higher wet tensile strength. For example,products such as pre-moistened towels or hard-surface cleaning wipes mayhave basis weights above 70 gsm, such as from 80 gsm to 150 gsm. Suchproducts can have CDWT values of 500 g/in or greater, with S-CDWT valuesof about 150 g/in or less, more specifically about 100 g/in or less, andmost specifically about 50 g/in or less, with similar ranges possiblefor S-CDWT-M.

[0132] Dispersibility

[0133] Prior efforts to measure dispersibility of webs, whether dry orpremoistened, have commonly relied on systems in which the web wasexposed to shear while in water, such as measuring the time for a web tobreak up while being agitated by a mechanical mixer. The constantexposure to shear offers an unrealistic and overly optimistic test forproducts designed to be flushed in a toilet, where the level of shear isweak and extremely brief. Once the product has passed through the neckof the toilet and entered a septic tank, shear rates may be negligible.Further, the product may not be fully wetted with water from the toiletbowl when it is flushed, or rather, there may not have been adequatetime for the wetting composition of the product to have been replacedwith the water of the toilet bowl when the momentary shear of flushingis applied. Thus, previous measurements of dispersibility could suggestthat a product is dispersible when, in fact, it may be poorly suited forseptic system.

[0134] For a realistic appraisal of dispersibility, it is believed thata relatively static measure is needed to better simulate the low shearthat real products will experience once they have become fully wettedwith water from the toilet. Thus, a test method for dispersibility hasbeen developed which does not rely on shear and which provides animproved means of assessing suitability of a product for a septicsystem. In this method, the tensile strength of a product is measured inits original, wetted form (the CDWT measurement described above) andafter the product has been soaked in a second solution for one hour(either the S-CDWT or S-CDWT-M test). The second solution can be eitherdeionized water for determination of the “Deionized Dispersibility”value or hard water (according to the S-CDWT-M test) for determinationof the “Hard Water Dispersibility” value. In either case, theDispersibility is defined as (1 minus the ratio of the cross-directionwet tensile strength in the second solution divided by the originalcross-direction wet tensile strength) * 100%. Thus, if a pre-moistenedwipe loses 75% of its CD wet tensile strength after soaking in hardwater for one hour, the Hard Water Dispersibility is (1-0.25)*100%=75%.The articles of the present invention can have a DeionizedDispersibility of 80% or greater, more specifically 90% or greater,specifically still 95% or greater, and can have a DeionizedDispersibility of about 100%. The articles of the present invention canhave a Hard Water Dispersibility of 70% or greater, more specifically80% or greater, specifically still about 90% or greater, and can have aDeionized Dispersibility of about 100%.

[0135] Method of Making Wet Wipes

[0136] The pre-moistened wipes of the present invention can be made inseveral ways. In one embodiment, the polymer composition is applied to afibrous substrate as part of an aqueous solution or suspension, whereinsubsequent drying is needed to remove the water and promote binding ofthe fibers. In particular, during drying, the binder migrates to thecrossover points of the fibers and becomes activated as a binder inthose regions, thus providing acceptable strength to the substrate. Forexample, the following steps can be applied:

[0137] 1. Providing an absorbent substrate that is not highly bonded(e.g., an unbonded airlaid, a tissue web, a carded web, fluff pulp,etc.).

[0138] 2. Applying an polymer composition to the substrate, typically inthe form of a liquid, suspension, or foam.

[0139] 3. Drying the substrate to promote bonding of the substrate. Thesubstrate may be dried such that the peak substrate temperature does notexceed 160° C., or 140° C., or 120° C., 110° C., or 100° C. In oneembodiment, the substrate temperature does not exceed 80° C. or 60° C.

[0140] 4. Applying a wetting composition to the substrate.

[0141] 5. Placing the wetted substrate in roll form or in a stack andpackaging the product.

[0142] Application of the polymer composition to the substrate can be bymeans of spray; by foam application; by immersion in a bath; by curtaincoating; by coating and metering with a wire-wound rod; by passage ofthe substrate through a flooded nip; by contact with a pre-meteredwetted roll coated with the binder solution; by pressing the substrateagainst a deformable carrier containing the polymer composition, such asa sponge or felt, to effect transfer into the substrate; by printingsuch as gravure, inkjet, or flexographic printing; and any other meansknown in the art.

[0143] In the use of foams to apply a polymer binder, the mixture isfrothed, typically with a foaming agent, and spread uniformly on thesubstrate, after which vacuum is applied to pull the froth through thesubstrate. Any known foam application method can be used, including thatof U.S. Pat. No. 4,018,647, “Process for the Impregnation of a Wet FiberWeb with a Heat Sensitized Foamed Latex Binder,” issued Apr. 19, 1977 toWietsma, the entirety of which is herein incorporated by reference.Wietsma discloses a method wherein a foamed latex is heat-sensitized bythe addition of a heat-sensitizer such as functional siloxane compoundsincluding siloxane oxyalkylene block copolymers and organopolysiloxanes.Specific examples of applicable heat-sensitizers and their use thereoffor the heat sensitization of latices are described in the U.S. Pat.Nos. 3,255,140; 3,255,141; 3,483,240 and 3,484,394, all of which areincorporated herein by reference. The use of a heat-sensitizer is saidto result in a product having a very soft and textile-like hand comparedto prior methods of applying foamed latex binders.

[0144] The amount of heat-sensitizer to be added is dependent on, interalia, the type of latex used, the desired coagulation temperature, themachine speed and the temperatures in the drying section of the machine,and will generally be in the range of about 0.05 to about 3% by weight,calculated as dry matter on the dry weight of the latex; but also largeror smaller amounts may be used. The heat sensitizer can be added in suchan amount that the latex will coagulate far below the boiling point ofwater, for instance at a temperature in the range of 35° C. to 95° C.,or from about 35° C. to 65° C.

[0145] Without wishing to be bound by theory, it is believed that adrying step after application of the binder solution and beforeapplication of the wetting composition enhances bonding of a fibroussubstrate by driving the binder to fiber crossover points as moisture isdriven off, thus promoting efficient use of the binder. However, in analternative method, the drying step listed above is skipped, and thepolymer composition is applied to the substrate followed by applicationof the wetting composition without significant intermediate drying. Inone version of this method, the polymer composition selectively adheresto the fibers, permitting excess water to be removed in an optionalpressing step without a significant loss of the binder from thesubstrate. In another version, no significant water removal occurs priorto application of the wetting composition. In yet another alternativemethod, the polymer composition and the wetting composition are appliedsimultaneously, optionally with subsequent addition of water-compatibleorganic solvent.

[0146] The present invention is further illustrated by the followingexamples, which are not to be construed in any way as imposinglimitations upon the scope thereof. On the contrary, it is to be clearlyunderstood that resort may be had to various other embodiments,modifications, and equivalents thereof which, after reading thedescription herein, may suggest themselves to those skilled in the artwithout departing from the spirit of the present invention and/or thescope of the appended claims.

[0147] As used herein, the “thickness” of a web is measured with a 3-inacrylic plastic disk connected to the spindle of a Mitutoyo DigimaticIndicator (Mitutoyo Corporation, 31-19, Shiba 5-chome, Minato-ku, Tokyo108, Japan) and which delivers a net load of 0.05 psi to the samplebeing measured. The Mitutoyo Digimatic Indicator is zeroed when the diskrests on a flat surface. When a sample having a size at least as greatas the acrylic disk is placed under the disk, a thickness reading can beobtained from the digital readout of the indicator. Water-dispersiblesubstrates of the present invention can have any suitable thickness,such as from about 0.1 mm to 5 mm. For wet wipes, thicknesses can be inthe range of 0.2 mm to about 1 mm, more specifically from about 0.3 mmto about 0.7 mm. Thickness can be controlled, for example, by theapplication of compaction rolls during or after web formation, bypressing after binder or wetting composition has been applied, or bycontrolling the tension of winding when forming a roll good.

[0148] The use of the platen method to measure thickness gives anaverage thickness at the macroscopic level. Local thickness may vary,especially if the product has been embossed or has otherwise been givena three-dimensional texture.

EXAMPLE 1

[0149] The nine binder solutions shown below were applied via a #20wire-wound rod to 10 identical water-dispersible, wet-laid webs composedof BFE rayon fibers (1.5 d×25 mm). The fabric samples were dried in aforced-air oven at 500° C. The add-on level was between 150 and 200 wt %based on the total weight of the fabric. The nonwoven sheets were cut toprovide 1 inch×3 inch strips from each sheet. The strips were tested forCDWT and SCDWT according to the following procedure.

[0150] CDWT:

[0151] The 1″×3″ strips from the 10 nonwoven sheets were soaked in thewipe solutions #1-#10 for 12 hours. The samples were removed from thesolutions and tested for tensile strength in the cross direction usingthe procedure outlined above.

[0152] SCDWT:

[0153] The 1″×3″ strips from the 10 nonwoven sheets were soaked in asolution of 200 ppm Ca²⁺ for 1 hour. The samples were removed from thesolutions and tested for tensile strength in the cross direction usingthe procedure outlined above.

[0154] The results are shown in Table 4 below. TABLE 4 TechnicalPerformance of Kao's Binder Binder Binder Solution Type Wipe solutionCDWT SCDWT 1 Sodium 20% propylene 1190 gm/in 1.4 gm/in  carboxymethylglycol, 2.5% cellulose CaCl₂.2H₂O (“CMC”) 2 Sodium CMC 20% propylene1138 gm/in 8.5 gm/in  glycol, 6% ZnSO₄.7H₂O 3 Sodium 20% propylene  480gm/in 77 gm/in polyacrylate glycol, 2.5% (Mwt = 400,000) CaCl₂.2H₂O 4Sodium 20% propylene  359 gm/in 260 gm/in  polyacrylate glycol, 6% (Mwt= 400,000) ZnSO₄.7H₂O 5 Blend 83% 20% propylene 1207 gm/in 13 gm/inSodium glycol, 6% polyacrylate ZnSO₄.7H₂O (Mwt = 400,000), 17% RhoplexNW-1715K (T_(g) = ˜ −15 C) 6 Blend 83% 20% propylene 1288 gm/in 34 gm/inSodium glycol, 2.5% polyacrylate CaCl₂.2H₂O (Mwt = 400,000), 17% Rovene4457 (T_(g) = ˜ −7 C) 7 Blend 83% 20% propylene  648 gm/in 42 gm/inSodium glycol, 6% polyacrylate ZnSO₄.7H₂O (Mwt = 400,000), 17% Rovene4457 (Tg = ˜ −7 C) 8 Blend 83% 20% propylene 1387 gm/in 50 gm/in Sodiumglycol, 2.5% polyacrylate CaCl₂.2H₂O (Mwt = 400,000), 17% Rovene 4817(T_(g) = ˜ −4 C) 9 Blend 83% 20% propylene  778 gm/in 44 gm/in Sodiumglycol, 6% polyacrylate ZnSO₄.7H₂O (Mwt = 400,000), 17% Rovene 4817(T_(g) = ˜ −4 C)

[0155] It should be understood, of course, that the foregoing relatesonly to certain disclosed embodiments of the present invention and thatnumerous modifications or alterations may be made therein withoutdeparting from the spirit and scope of the invention as set forth in theappended claims.

What is claimed is:
 1. A composition comprising: sodium polyacrylate;and a styrene emulsion.
 2. The composition of claim 1, wherein thestyrene emulsion is selected from styrene acrylic or styrene-butadieneemulsion.
 3. The composition of claim 1, wherein the compositioncomprises approximately 50% to 95% by weight sodium polyacrylate andapproximately 5% to 50% by weight styrene emulsion.
 4. The compositionof claim 1, wherein the composition comprises approximately 83% byweight sodium polyacrylate and approximately 17% by weight styreneemulsion.
 5. The composition of claim 1, wherein said composition issprayable.
 6. A composition comprising: a polymer containing carboxylategroups and having a flexible polymer chain; and an emulsion latexpolymer.
 7. The composition of claim 6, wherein the compositioncomprises approximately 50% to 95% by weight carboxylategroup-containing polymer and approximately 5% to 50% by weight emulsionlatex polymer.
 8. The composition of claim 6, wherein the compositioncomprises approximately 83% by weight carboxylate group-containingpolymer and approximately 17% by weight emulsion latex polymer.
 9. Thecomposition of claim 6, wherein said composition is sprayable.
 10. Abinder composition for binding fibrous material into an integral web,said binder composition comprising the composition of claim
 6. 11. Anonwoven fabric comprising fibrous material and a binder material, saidbinder material comprising the composition of claim
 6. 12. A fibroussubstrate comprising: fibrous material; and a binder composition forbinding said fibrous material into an integral web, said bindercomposition comprising a polymer containing carboxylate groups andhaving a flexible polymer chain and a styrene emulsion.
 13. Awater-dispersible article comprising the fibrous substrate of claim 12.14. A wet wipe comprising: a fibrous material; a binder composition forbinding said fibrous material into an integral web, said bindercomposition comprising a polymer containing carboxylate groups andhaving a flexible polymer chain and a styrene emulsion; and said fibrousmaterial being wetted by a wetting solution containing at least about 5weight percent water-compatible organic solvent.
 15. A methodcomprising: combining a polymer containing carboxylate groups and havinga flexible polymer chain; and an emulsion latex polymer.
 16. A method ofmaking a wet wipe comprising: forming a substrate of fibrous material;applying to said substrate a binder composition for said fibrousmaterial comprising a polymer containing carboxylate groups and having aflexible polymer chain and a styrene emulsion; and applying to saidsubstrate a wetting solution containing at least about 5 weight percentwater-compatible organic solvent, whereby the wet wipe retains wetstrength in said wetting solution and whereby the wet wipe isdispersible in water containing up to about 200 ppm of one or moremultivalent ions.
 17. The method of claim 16, wherein said bindercomposition is applied to said fibrous material by spraying.
 18. Amethod comprising: applying to a substrate of fibrous material; a bindercomposition for said fibrous material comprising a polymer containingcarboxylate groups and having a flexible polymer chain and an emulsionlatex polymer, whereby said binder composition is applied by spraying.